This invention is concerned with an automatic guide system which manages multiple automatic guided vehicles (AGV's).
This invention especially relates to the sensor unit for traffic control that is capable of controlling the transit, stop or deadlocking status of each AGV according to the transit priority of each AGV and to detect the transit direction of an AGV in a traffic control area where the AGV is in danger of crashing into another AGV.
In the automatic guide system which manages the operation of multiple AGV's, a traffic control method is always necessary.
The two methods of communication between the AGV and the control system are point-to-point methods and space communication methods. The space communication method is often used. As in conventional space communication methods, the devices exchange information by using Phase Shift Keying (PSK). It is, however, difficult to implement PSK in an AGV system when the controller is driven by a Programmable Logic Controller (PLC).
On the other hand, the point to point method which communicates by using Frequency Shift Keying (FSK) and controls the AGV's running direction thereby, has had the problems that the capacity of the oscillator becomes bulky, and the hardware to select an operating frequency has to exist in each AGV. It is the object of this invention to solve these conventional problems.